Cationic epoxide resinous composition

ABSTRACT

Polyepoxide resins are reacted with a molar excess of a primary amine to form an amine terminated resin, the amine groups of which are then reacted with a monoepoxide. The primary amine is a mixture of an aliphatic monoamine and an aliphatic diamine which contains one primary amine group and one tertiary amine group. The resinous reaction products can be salted with an acid and can be dissolved or dispersed in water. The aqueous dispersions or solutions can then be formulated into primer coatings for metal objects.

CROSS REFERENCE TO RELATED APPLICATIONS

This is a continuation-in-part of application, Ser. No. 858,135, datedDec. 7, 1977 (now abandoned).

BACKGROUND OF THE INVENTION

The field of art to which this invention pertains is synthetic resinscontaining a hydrophilic group, said resins being soluble or dispersiblein water when salted.

Industrial coating processes utilizing aqueous dispersions or solutionsof organic resinous film forming compositions continue to grow inimportance. The aqueous coating compositions are used in variousapplications, such as spray coating, flow coating and electrodepositioncoating processes. Particularly useful organic resinous film formingcompositions are cationic compositions which, primarily, are used inprimer paints for metals. Such cationic compositions which contain aminenitrogen groups have superior corrosion resistance when formulated intoprimer paints.

The coating of electrically conductive substrates by electrodepositionis an important industrial process. In this process, a conductivearticle is immersed as one electrode in a coating composition made froman aqueous dispersion of film-forming polymer. An electric current ispassed between the article and a counterelectrode in electrical contactwith the aqueous dispersion until a desired amount of coating isproduced on the article. The article to be coated can be made the anodeor the cathode depending upon the ionic nature of the coating system.

There are certain disadvantages in anodic deposition processes. Anodicdeposition on ferrous metals tends to discolor the electrodeposited filmand phosphate conversion coatings, which are commonly applied to a metalsurface before an organic coating composition is deposited thereon, tendto be stripped from the metal under anodic deposition conditions. Inaddition, it is a peculiarity of anodic electrodeposition coatingmethods that nascent oxygen is produced at the anode which can reactwith the resinous coating composition to produce bubbles or voids in thedeposited coatings.

The use of cathodic electrodepositable compositions tends to alleviatethe discoloration problems and to give improved resistance properties.Although nascent hydrogen develops at the cathode during theelectrodeposition process, no metal ions pass into the coating solutionor are present in the deposited film. Generally, the amount of nascenthydrogen produced at the cathode does not have the same deleteriouseffect on the properties of the deposited film as does the nascentoxygen produced during anodic deposition.

Cationic coating compositions generally are derived from resinouscompositions containing a basic nitrogen atom which can be salted withan acid and then be dissolved or dispersed in water. Sufficient basicnitrogen atoms should be present so that dispersibility or solubilitycan be obtained with a minimum amount of acid. If the coating bath isvery acidic, considerable corrosion problems with the metal tanks,piping systems and other equipment are encountered.

SUMMARY OF THE INVENTION

This invention pertains to resinous compositions. In particular thisinvention relates to cationic resinous coating compositions. Moreparticularly, this invention pertains to cationic resinous coatingcompositions which when salted with an acid are dispersible or solublein water.

The soluble and fusible resinous composition of this invention is madefrom a polyepoxide resin, a mixture of primary amines and a monoepoxide.The polyepoxide resin is derived from a diol and an epihalohydrin andhas a 1,2-epoxide equivalent weight of about 180 to about 650. One ofthe primary amines of the mixture is an aliphatic monoamine containingabout 8 to about 18 carbon atoms, one primary amine group and no othergroups which are reactive with epoxide groups. The other primary amineis an aliphatic diamine which contains one primary amine group and onetertiary amine group and no other groups reactive with epoxide groups.The amines in the mixture are within the mol ratios of about 2:1aliphatic monoamine:aliphatic diamine to about 1:3 aliphaticmonoamine:aliphatic diamine. The monoepoxide contains one 1,2-epoxidegroup per molecule, no other groups reactive with amine groups and hasabout 8 to about 24 carbon atoms per molecule. In the composition, thepolyepoxide resin, the primary amine mixture and the monoepoxide arereacted in the mol of about 5:6:2 to 2:3:2.

The resinous compositions of this invention contain tertiary aminegroups within the polymeric chain as well as pendant tertiary aminegroups. The compositions also contain aliphatic hydroxyl groups whichare present in the epoxide resin and which are formed when the primaryamines react with the epoxide groups. Upon partial salting with an acid,the resins are readily dissolved or dispersed in water. Such aqueouscompositions can be formulated into coating compositions which areparticularly useful as primers for metals.

DESCRIPTION OF THE INVENTION

The compositions of this invention are the reaction products ofpolyepoxide resins and mono primary amines further reacted with amonoepoxide. These compositions can be represented by the formula

    M (AE).sub.n AM

wherein

A represents a reacted primary amine,

E represents a reacted polyepoxide resin,

M represents a reacted monoepoxide, and

n represents an integer of 2 to 5.

In the above formula, the AE linkages and the AM linkages which areformed by the reaction of an amine group and an epoxide group, can berepresented by the skeletal formula ##STR1## wherein R is a hydrocarbongroup. The nitrogen atom is a tertiary amine group and can be saltedwith an acid. The OH group is available for crosslinking reactions.

The polyepoxide resins useful in this invention are glycidyl polyethersof polyhydric phenols and polyhydric alcohols and contain more than oneup to two 1,2-epoxide groups per molecule. Such polyepoxide resins arederived from a dihydric phenol or a dihydric alcohol and anepihalohydrin and have an epoxide equivalent weight of about 180 toabout 650. Examples of epihalohydrins are epichlorohydrin,epibromohydrin and epiiodohydrin with epichlorohydrin being preferred.Dihydric phenols and dihydric alcohols are exemplified by resorcinol,hydroquinone, p p-dihydroxydiphenyl propane (or Bisphenol A as it iscommonly called), p,p'-dihydroxybenzophenone, p,p'-dihydroxy diphenyl,p,p'-dihydroxydiphenyl ethane, bis(2-hydroxynaphthyl) methane,1,5-dihydroxynaphthalene, ethylene glycol, propylene glycol,1,4-butanediol, hydrogenated Bisphenol A, 1,4-cyclohexanediol,1,3-cyclopentanediol, cyclohexane dimethanol, and the like. Thesepolyepoxide resins are well known in the art and are made in the desiredmolecular weights by reacting the epihalohydrin and the diol in variousratios, or by reacting a dihydric phenol with a lower molecular weightpolyepoxide resin. Preferred polyepoxide resins are the glycidylpolyethers of Bisphenol A having an epoxide equivalent weight of about350 to about 650 and, most preferred, an epoxide equivalent weight ofabout 425 to about 550. As used in this invention one mol of thepolyepoxide resin is considered to have a molecular weight which istwice the epoxide equivalent weight.

The amines used in this invention are a mixture of aliphatic monoamineswhich contain one primary amine group per molecule and aliphaticdiamines which contain one primary amine group and one tertiary aminegroup per molecule. The aliphatic monoamines contain about 8 to about 18carbon atoms, only one amine group, a primary amine group, and no othergroups which are reactive with epoxide groups. Examples of such aminesare 2-ethylhexylamine, 2,4-diisopropylhexylamine, nonylamine,decylamine, dodecylamine, hexadecylamine, and octadecylamine. Alsoincluded are the fatty amines which are named after the fatty acids fromwhich theu are derived, e.g., laurylamine, myristylamine, palmitylamine,stearylamine, oleylamine, linoleylamine and linolenylamine. Fatty aminesalso include mixture of such amines which are derived from correspondingmixed fatty acids and are named after the naturally occurring oils andwaxes from which they are derived, e.g., cocoanut amine, tallow amine,hydrogenated tallow amine and soya amine. The preferred aliphaticmonoamines are those amines which contain about 12 to about 16 carbonatoms per molecule.

The aliphatic diamines contain only one primary amine group and only onetertiary amine group and no other groups which are reactive with epoxidegroups. These diamines can be represented by the formula ##STR2##wherein each R is an alkyl group which contains 2 to 6 carbon atoms andR₁ is hydrogen or an alkyl group which contains one or 2 carbon atoms.The preferred diamine is 3-diethylaminopropylamine.

The monoamine and the diamine are present in the mixture in the molarratio of about 2 mols of monoamine to one mol of diamine to about onemol of monoamine to 3 mols of diamine. Preferred ratios are equimolaramounts of the two amines as well as 1 mol of the monoamine and 3 molsof the diamine.

The monoepoxides which are used in this invention to modify thepolyepoxide/amine reaction products are those compounds which containone 1,2-epoxide group per molecule and no other groups which arereactive with amine groups and which contain from about 8 to about 24carbon atoms per molecule. Examples of monoepoxides are epoxidizedhydrocarbons, epoxidized unsaturated fatty esters, monoglycidyl ethersof aliphatic alcohols and monoglycidyl esters of monocarboxylic acids.Examples of such monoepoxides are: epoxidized unsaturated hydrocarbonswhich contain 8 to 24 carbon atoms, e.g., octylene oxide, decyleneoxide, dodecylene oxide and nonadecylene oxide; epoxidized monoalcoholesters of unsaturated fatty acids wherein the fatty acids contain about8 to about 18 carbon atoms and the alcohol contains 1 to 6 carbon atoms,e.g., epoxidized methyl oleate, epoxidized n-butyl oleate, epoxidizedmethyl palmitoleate, epoxidized ethyl linoleate and the like;monoglycidyl ethers of monohydric alcohols which contain 8 to 20 carbonatoms, e.g., octyl glycidyl ether, decyl glycidyl ether, dodecylglycidyl ether, tetradecyl glycidyl ether, hexadecyl glycidyl ether andoctadecyl glycidyl ether; monoglycidyl esters of monocarboxylic acidswhich contain 8 to 20 carbon atoms, e.g., the glycidyl ester of capricacid, the glycidyl ester of lauric acid, the glycidyl ester of stearicacid, the glycidyl ester of arachidic acid and the glycidyl esters ofalpha, alpha-dialkyl monocarboxylic acids described in U.S. Pat. No.3,178,454 which is hereby incorporated by reference. Examples of suchglycidyl esters are those derived from about 9 to about 19 carbon atoms,particularly Versatic 911 Acid, a product of Shell Oil Company, whichacid contains 9 to 11 carbon atoms. The preferred monoepoxides are themonoglycidyl ethers of monohydric alcohols which alcohols contain 8 to20 carbon atoms.

In preparing the compositions of this invention, the reaction of theprimary amine mixture and the polyepoxide resin is conducted with theamines in excess to prevent gelation of the reactants. The molar ratioof polyepoxide resin to primary amines will vary from about 5:6 to about2:3 and, preferably, about 3:4. As calculated in this invention, thismolar ratio is actually the equivalent ratio, i.e., the ratio of 5:6 to2:3 is based on 1,2-epoxide groups and primary amine hydrogen atoms.After substantially all of the epoxide groups of the polyepoxide resinhave reacted, the resulting resinous amine terminated polymer is thenreacted with a monoepoxide. The amount of monoepoxide used is one mol ofmonoepoxide per each amine hydrogen which remains in the polymer, i.e.,2 mols of monoepoxide per mol of primary amine/polyepoxide reactionproduct. The molar ratio of polyepoxide resin to primary amine tomonoepoxide is 5:6:2 to 2:3:2. Alternatively, the polyepoxide resin andthe monoepoxide can be added together rather than consecutively to themixture of amines. The molar ratio of components, however, will be thesame as set forth hereinabove. The monoepoxide modified resinousproducts produce coating compositions which have enhanced flexibility,sufficient softness to make good primers, improved corrosion resistanceand good insulating properties when used in electrodeposition processes.

As set forth hereinbefore, the primary amines used in the process ofthis invention are a mixture of long chain monoprimary amines anddiamines which contain one primary amine group and one tertiary aminegroup. If all monoprimary amine is used, the resulting resinous productsrequire a high equivalence of acid to form salts which can be dispersedin water. The aqueous baths of these salts have low pH's which areundesirable because of corrosion problems. If all diamine is used, theresins can be readily dispersed in water with low equivalent amounts ofacid and, therefore, practically neutral baths. However, such productsdo not have sufficient flexibility, film flow, corrosion resistance, andinsulation properties to make good primers. It has been found that amolar mixture of monoamine to diamine of 2:1 to 1:3 gives a good balanceof properties.

Normally, the reaction of two difunctional compounds results in a linearpolymer, e.g., polyesters formed from ethylene glycol and terephthalicacid. The reaction of a diepoxide and a primary amine, two difunctionalcompounds, should result in a linear polymer. However, under someconditions, such as when the two compounds are mixed together and heatedto a reaction temperature, crosslinking and gel formation can occur. Itis postulated that this gel formation results from the reaction of epoxygroups and the hydroxyl groups which are in the epoxy resin or resultfrom the reaction of epoxy groups and amines. The epoxy-hydroxylreaction is catalyzed by tertiary amine groups which are present in suchamines as 3-diethylaminopropylamine or which are formed when a primaryamine reacts with 2 epoxy groups. In order to minimize theepoxy-hydroxyl reaction and to prevent gel formation, the compositionsof this invention are made by adding the epoxide compounds to the aminemixtures at the reaction temperature of about 50° C. to about 150° C.and, preferably, at about 75° C. to about 100° C. The rate of additionof the epoxide compounds is such that there is substantially no build-upof epoxy groups which will be free to react with hydroxyl groups. Thisaddition is so adjusted that it does not, substantially, exceed theepoxy-amine reaction rate. Ideally, the addition rate is such that theepoxy group will react with a primary or formed secondary amine group assoon as it contacts the amine mixture. The addition time will varydepending upon the reaction temperature, but generally will be fromabout 30 minutes to about 6 hours.

As stated hereinbefore, the polyepoxide resin and the monoepoxide can beadded simultaneously to the primary amine mixture. Preferably, thepolyepoxide resin is added to and reacted with the amine mixturefollowed by addition and reaction of the monoepoxide.

The reaction can be conducted in the absence of solvents. However, inview of the resinous nature of the products, it is preferred to conductthe reaction in an organic solvent. Any organic liquid which is asolvent for the reactants and reaction product and is nonreactive withepoxide groups and amine groups under the reaction conditions can beused. Such solvents include hydrocarbons, ethers, alcohols, polyols,ether alcohols, and the like. Preferred solvents are water solublesolvents, e.g., alkylene glycol mono and diethers. The amount of solventused can be any amount which is sufficient to render the reactants fluidat the reaction temperature. This amount of solvent will vary from about0 to about 75 weight percent based on the total weight of the solution,and preferably 20 to 40 weight percent.

As stated hereinbefore, the resinous compositions of this invention arepreferably made into aqueous coating compositions. In order to do this,it is necessary to add a neutralizing agent. Neutralization isaccomplished by the salting of all or part of the amine groups by awater soluble organic or inorganic acid, e.g., formic acid, acetic acid,phosphoric acid, sulfuric acid, hydrochloric acid, and the like. Apreferred acid is formic acid. The extent of neutralization depends uponthe particular resin and it is only necessary that sufficient acid beadded to solubilize or disperse the resin.

Aqueous coating compositions made from the resinous compositions of thisinvention can have a pH of about 3 to about 10, but preferably the pHwill be about 5.0 to about 7.5 and, most preferably, about 6 to about 7.The amount of acid will vary from about 0.2 to about 1 equivalent foreach amine nitrogen equivalent in the resin, but, preferably, about 0.25to about 0.7 equivalent and, most preferably, about 0.3 to about 0.4equivalent of formic acid. If the pH is too low, corrosion of equipmentis a problem. Electrocoating baths with low pH's have high conductivitywhich causes the utilization of more current. More gassing occurs at thecathode causing rough coatings. The coatings have lower rupture voltageand the throwing power (the ability to coat protected areas) isdecreased. If the pH is high, the resin generally is difficult todissolve or disperse and the resulting solution or dispersion isunstable. A pH close to neutral is preferred in order to obtain the bestbalance of coating properties and bath stability.

The resinous composition of this invention, when made into a coatingcomposition will be cured with a crosslinking agent. Such crosslinkingagents are aminoplast resins, phenolplast resins and blockedpolyisocyanates. Suitable aminoplast resins are the reaction products ofureas and melamines with aldehydes further etherified in some cases withan alcohol. Examples of aminoplast resin components are urea, ethyleneurea, thiourea, melamine, benzoguanamine and acetoguanamine. Aldehydesuseful in this invention are formaldehyde, acetaldehyde andpropionaldehyde. The aminoplast resins can be used in the alkylol formbut, preferably, are utilized in the ether form wherein the etherifyingagent is a monohydric alcohol containing from 1 to about 8 carbon atoms.Examples of suitable aminoplast resins are methylol urea,dimethoxymethylol urea, butylated polymeric urea-formaldehyde resins,hexamethoxymethyl melamine, methylated polymeric melamine-formaldehyderesins and butylated polymeric melamine-formaldehyde resins. Aminoplastresins and their methods of preparation are described in detail in"Encyclopedia of Polymer Science and Technology", Volume 2, pages 1-91,Interscience Publishers (1965), which is hereby incorporated byreference.

Phenolplast resins are the reaction products of phenols and aldehydeswhich contain reactive methylol groups. These compositions can bemonomeric or polymeric in nature depending on the molar ratio of phenolto aldehyde used in the initial condensation reaction. Examples ofphenols which can be used to make the phenolplast resins are phenol, o,m, or p-cresol, 2,4-xylenol, 3,4-xylenol, 2,5-xylenol, cardanol,p-tert-butylphenol, and the like. Aldehydes useful in this reaction areformaldehyde, acetaldehyde and propionaldehyde. Particularly usefulphenolplast resins are polymethylol phenols wherein the phenolic groupis etherified with an alkyl, e.g., methyl or ethyl, group. Phenolplastresins and their methods of preparation are described in detail in"Encyclopedia of Polymer Science and Technology", Volume 10, pages 1-68.Interscience Publishers (1969), which is hereby incorporated byreference.

The amount of aminoplast or phenolplast resin used with the resinouscompositions of this invention is about 8 weight percent to about 30weight percent of the total vehicle solids weight and, preferably, about15 to about 20 weight percent.

Useful blocked polyisocyanates are those which are stable in thedispersion systems at ordinary room temperature and which react with theresinous product of this invention at elevated temperatures.

In the preparation of the blocked organic polyisocyanate, any suitableorganic polyisocyanate can be used. Representative examples are thealiphatic compounds such as trimethylene, tetramethylene,pentamethylene, hexamethylene, 1,2-propylene, 1,2-butylene, 2,3-butyleneand 1,3-butylene diisocyanates; the cycloalkylene compounds such as1,3-cyclopentane, 1,4-cyclohexane, and 1,2-cyclohexane diisocyanates;the aromatic compounds such as m-phenylene, p-phenylene, 4,4'-diphenyl,and 1,4-naphthalene diisocyanates; the aliphatic-aromatic compounds suchas 4,4'-diphenylene methane, 2,4- or 2,6-tolylene, or mixtures thereof,4,4'-toluidine, and 1,4-xylylene diisocyanates; the triisocyanates suchas triphenyl methane-4,4'4"-triisocyanate, 1,3,5-triisocyanate benzeneand 2,4,6-triisocyanate toluene; and the tetraisocyanates such as4,4'-diphenyl-dimethyl methane-2,2',5,5'-tetraisocyanate; thepolymerized polyisocyanates such as tolylene diisocyanate dimers andtrimers, polymethylenepolyphenylene polyisocyanates having NCOfunctionalities of 2 to 3, and the like.

In addition, the organic polyisocyanate can be prepolymer derived from apolyol such as glycols, e.g. ethylene glycol and propylene glycol, aswell as other polyols such as glycerol, trimethylolpropane, hexanetriol,pentaerythritol, and the like, as well as mono-ethers, such asdiethylene glycol, tripropylene glycol and the like and polyethers,i.e., alkylene oxide condensates of the above. Among the alkylene oxidesthat may be condensed with these polyols to form polyethers are ethyleneoxide, propylene oxide, butylene oxide, styrene oxide and the like.These are generally called hydroxyl-terminated polyethers and can belinear or branched. Especially useful polyether polyols are thosederived from reacting polyols such as ethylene glycol, diethyleneglycol, triethylene glycol, 1,4-butylene glycol 1,3-butylene glycol,1,6-hexanediol, and their mixtures; glycerol, trimethylolethane,trimethylolpropane, 1,2,6-hexanetriol, pentaerythritol,dipentaerythritol, tripentaerythritol, polypentaerythritol, sorbitol,methyl glucosides, sucrose and the like with alkylene oxides such asethylene oxide, propylene oxide, their mixtures, and the like.

Any suitable aliphatic, cycloaliphatic, aromatic, alkyl monoalcohol andphenolic compound can be used as a blocking agent in the practice of thepresent invention, such as lower aliphatic alcohols, such as methyl,ethyl, chloroethyl, propyl, butyl, amyl, hexyl, heptyl, octyl, nonyl,3,3,5-trimethylhexanol, decyl and lauryl alcohols, and the like; thearomatic-alkyl alcohols, such as phenylcarbinol, methylphenylcarbinol,ethyl glycol monoethyl ether, ethyl glycol monobutyl ether and the like;the phenolic compounds such as phenol itself, substituted phenols inwhich the substituents do not adversely affect the coating operations.Examples include cresol, nitrophenol, chlorophenol and t-butyl phenol.Additional blocking agents include tertiary hydroxyl amines, such asdiethylethanolamine and oximes, such as methylethyl ketoxime, acetoneoxime and cyclohexanone oxime, and caprolactam.

The blocked polyisocyanate is formed by reacting a sufficient quantityof blocking agent with the organic polyisocyanate to insure that no freeisocyanate groups are present.

The amount of blocked polyisocyanate used will vary from about 15 weightpercent to about 40 weight percent based on the total vehicle solidsweight and preferably about 20 weight percent to about 25 weightpercent.

The aqueous coating compositions can also contain pigments, couplingsolvents, anti-oxidants, surface-active agents and the like. Thepigments are of the conventional type and are one or more of suchpigments as iron oxides, lead oxides, strontium chromate, carbon black,titanium dioxide, talc, barium sulfate, barium yellow, cadmium red,chromic green, lead silicate and the like. The amount of pigment usedwill vary from no pigment up to a pigment/binder ratio by weight of 2:1and preferably a pigment/binder ratio of about 1:1 to 1:4.

Coupling solvents are water soluble or partially water soluble organicsolvents for the resinous vehicles used in this invention. Examples ofsuch solvents are ethylene glycol monomethyl ether, ethylene glycolmonoethyl ether, ethylene glycol monobutyl ether, diethylene glycolmonobutyl ether, ethanol, isopropanol, n-butanol, and the like. Thesecoupling solvents are used in the amounts of 0 up to about 5 weightpercent of the total weight of the coating bath. The total bath solidsare kept within the range, based on the total bath weight, of about 5 toabout 20 weight percent and, preferably, about 12 to about 18 weightpercent.

In utilizing the resin of this invention, in electrodepositionprocesses, the electrocoating bath is prepared in an insulated containerwith an anode submersed in the bath and the object to be coated as thecathode. A direct electric current is applied using a voltage of 200 to300 volts for a time sufficient to obtain a coating of about 0.5 to 1mil, i.e., about 1 to 5 minutes. The coated object is then removed fromthe bath, rinsed and baked at 150° to 250° C. for 10 to 30 minutes toobtain a cured coating.

When used as dip coating primers, the resinous composition, curingagents, pigments, acid and water are formulated to a solids content ofabout 25 weight percent to about 35 weight percent in a dip tank. Metalobjects are passed through the tank, are allowed to drip to removeexcess paint and are baked at about 150° C. for about 10 to about 30minutes.

The following examples will describe the invention in more detail. Partsand percentages are parts and percentages by weight unless otherwisedesignated.

EXAMPLE 1

To a suitable reactor were added 50.1 parts of 3-diethylaminopropylamineand 24.3 parts of dodecylamine. A nitrogen gas flush and agitation werebegun. Heat was applied raising the temperature to 84° C. A solution of360.1 parts of a glycidyl polyether of Bisphenol A having an epoxideequivalent weight of 467 in 214.3 parts of propylene glycol methyl etherwas then added over a period of 2 hours and 2 minutes while keeping thetemperature between 91° C. and 96° C. Heating between 91° C. and 102° C.was continued for one hour and 30 minutes to ensure completeness of theepoxide-amine reaction. At 102° C. the addition of 65.5 parts of aglycidyl ether of mixed fatty alcohols containing predominantly n-octyland n-decyl groups, said glycidyl ether having an epoxide equivalentweight of 230, was begun and continued over 31 minutes with thetemperature rising to 106° C. Heating between 106° C. and 110° C. wascontinued for 2 hours and 52 minutes to ensure completeness of thereaction.

The epoxy-amine adduct solution (48.6 parts) was blended with abutylated melamine formaldehyde resin solution at 66.7 percent in amixture of 87.3 percent ethylene glycol methyl ether and 12.7 percentbutanol (9.0 parts). The blend was slowly added with stirring to asolution of 1.27 parts of formic acid (89 percent in water) and 102parts of water to form an almost clear solution. The solution was cooledto room temperature and was diluted with an additional 240 parts ofwater. This solution, having a pH of 5.9, was then placed in anelectrocoating tank. Steel panels were made the cathode in a directelectric circuit and were immersed in the solution. The panels werecoated 1 minute at 200 volts, at an initial current of 1 ampere whichquickly fell to about 0.1 ampere. The coated panels were removed fromthe bath, were rinsed with water and were baked at 190° C. for 20minutes. The coatings had a film thickness of 0.3 to 0.35 mil and werefairly smooth and glossy. The coatings were somewhat softened after 100double rubs with methylethyl ketone.

The epoxy-amine adduct solution (42.9 parts) was blended with 12.5 partsof an 80 percent solution in ethylene glycol monoethyl ether acetate ofa blocked polyisocyanate made from a polymethylene polyphenylisocyanatehaving an average functionality of 2.7 blocked with caprolactam on thebasis of one mol of caprolactam per NCO equivalent of thepolyisocyanate. This blend was slowly added with stirring to a solutionof 1.12 parts of formic acid (89 percent in water) and 104 parts ofwater. The solution was then further diluted with 240 parts of water.This solution, which had a pH of 6.2 was placed in an electrocoatingbath and steel panels were coated at the cathode of a direct electriccircuit at 200 volts for 1 minute. The initial current was 1.6 ampereswith a quick drop to 0.1 ampere. The coated panels were removed from thebath, rinsed with water and baked at 163° C. for 20 minutes. Thecoatings were somewhat rough and textured but had fair to good gloss andwere well cured. After 100 methylethyl ketone double rubs, the coatingsexhibited slight softening with quick recovery.

The epoxy-amine adduct solution (45.7 parts) was blended with a 10.6parts of a 75.7% solution in methylisobutyl ketone/ethylene glycolmonomethyl ether (53/47) of a blocked polyisocyanate made from apolymethylene polyphenyl polyisocyanate having an average functionalityof 2.4 blocked with 0.8 equivalents of caprolactam and 0.3 equivalentsof 2,2,4-trimethyl-1,3-pentanediol per NCO equivalent. This blend wasdissolved in a solution of 0.94 part of formic acid (89% in water) and343 parts of water. The resulting solution, pH-6.4, was made into anelectrocoating bath and steel panels were coated using 200 volts, 250volts and 300 volts for 2 minutes. Coatings having dry film thicknessesof 0.9-1.1 mils were obtained from the runs at 200 and 250 volts.Plating at 300 volts causes rupture of the coatings. The coated panelsfrom the 200 and 250 volt runs were removed from the bath, rinsed andbaked for 20 minutes at 163° C. The coatings had uniform moderatepinholing and a pencil hardness of H-2H. Methylethyl ketone, 100 doublerubs, definitely softened the coatings.

EXAMPLE 2

To a suitable reactor were added 135.2 parts of dodecylamine and 279.4parts of 3-diethylaminopropylamine. Agitation, a nitrogen flush and heatwere applied, raising the temperature to 112° C. A solution of 2020parts of the glycidyl polyether of Bisphenol A, having an epoxideequivalent weight of 470, in 1200 parts of propylene glycol methyl etherwas added over a period of 1 hour and 58 minutes with the temperaturebeing held between 98° C. and 114° C. After additional heating at 99° C.for 1 hour and 5 minutes, the addition of 365.4 parts of the glycidylether of mixed fatty alcohols described in Example 1 was begun andcompleted over a 28 minute period with the temperature rising to 102° C.Additional heating to 107° C. over 2 hours and 16 minutes was continuedto ensure completeness of the reaction.

After cooling to room temperature, 48.6 parts of the resinous productwere blended with 9 parts of the butylated melamine-formaldehyde resindescribed in Example 1 and were added to s solution of 1.27 parts offormic acid (89% in water) in 102 parts of water heated to 70° C. Thesolution was cooled to room temperature and was further diluted with 240parts of water. This solution, pH 5.8, was placed in an electrocoatingbath and was used to coat steel panels using 200 volts for 1 minute. Theinitial current was 1 ampere which quickly dropped to 0.1 ampere. Thecoated panels were removed from the bath, rinsed with water and baked at190° C. for 20 minutes. The resulting coatings had an average thicknessof 0.3 mil and a pencil hardness of 3H-4H. The coatings were fairlysmooth, glossy and well cured exhibiting only a slight effect after 100double rubs with methylethyl ketone.

EXAMPLE 3

Using the same procedure described in Example 1, 269.9 parts ofn-dodecylamine and 185.6 parts of 3-diethylaminopropylamine were reactedwith 2014.4 parts of a glycidyl polyether of Bisphenol A having anepoxide equivalent weight of 470 followed by reaction with 330.1 partsof the glycidyl ether of mixed fatty alcohols containing, predominantly,n-octyl and n-decyl groups, said glycidyl ether having an epoxideequivalent weight of 231. The reactions were carried out in 1200 partsof propylene glycol methyl ether.

Part of the above solution, 46.2 parts, was blended with 10.6 parts of a75.7% solution in methylisobutyl ketone/ethylene glycol monomethyl ether(53/47) of a blocked polyisocyanate made from a polyphenyl isocyanatehaving an average functionality of 2.4 blocked with 0.8 equivalents ofcaprolactam and 0.3 equivalents of 2,2,4-trimethyl 1-3-pentanediol perNCO equivalent. This blend was dissolved in a solution of 0.94 parts offormic acid (89% in water) and 343 parts of water. The resulting blend,pH=5.0, was placed in an electrocoating apparatus and steel panels werecoated at the cathode of a direct electric circuit. Panels were coatedat several voltages, 200 volts, 250 volts and 300 volts, for 2 minutes.All depositions drew a current of 1 ampere initially which quicklydropped off to 0.1 ampere. The panels were removed from the bath, rinsedwith water and baked at 163° C. for 20 minutes. The coatings on thepanels deposited at 200 volts had a dry film thickness of 0.4-0.5 mil,at 250 volts-0.5-0.6 mil and at 300 volts 0.7-0.9 mil. The pencilhardness of all the films was H-2H. The film appearance of the coatingsdeposited at 200 volts and 250 volts was smooth and glossy with moderatepinholing. The coatings deposited at 300 volts were very rough.

A repeat of the depositions using 0.84 part of formic acid in place ofthe 0.94 part, the bath pH being 5.3, gave comparable results.

EXAMPLE 4

Using the same procedure described in Example 1, 170.8 parts ofn-hexadecylamine and 268.8 parts of diethylaminopropyl amine werereacted with 1951.6 parts of the glycidyl polyether of Bisphenol Ahaving an epoxide equivalent weight of 470 in 1200 parts of propyleneglycol methyl ether followed by reaction with 408.8 parts of a glycidylether of mixed fatty alcohols containing predominantly n-dodecyl andn-tetradecyl groups, said glycidyl ether having an epoxide equivalentweight of 295.

An electrocoating bath was prepared from 91.4 parts of the resinsolution blended with 21.1 parts of the blocked polyisocyanate solutiondescribed in Example 1 (the polymethyl polyphenyl polyisocyanate blockedwith caprolactam and 2,2,4-trimethyl-1,3-pentanediol), 1.73 parts offormic acid (90% in water) and 687 parts of water. Steel panels werecoated using 250 volts for 30 seconds, 45 seconds, 60 seconds, 90seconds and 120 seconds. The coated panels were removed from the bath,rinsed with water and baked for 20 minutes at 165° C. The films werewell cured with a pencil hardness of 2H-3H. They softened slightly after100 double rubs with methylethyl ketone.

EXAMPLE 5

Using the same procedure described in Example 1, 225 parts ofn-dodecylamine and 155 parts of 3-diethylaminopropylamine were reactedwith a glycidyl polyether of Bisphenol A having an epoxide equivalentweight of 470 (2146 parts of a solution of the glycidyl polyether at73.8% solids in propylene glycol methyl ether), followed by reactionwith 274 parts of a glycidyl ether of mixed fatty alcohols containingpredominantly n-octyl and n-decyl groups, said glycidyl ether having anepoxide equivalent weight of 230.

To a suitable mixing tank were added 8.12 parts of the resin solutiondescribed above, 1.66 parts of ethylene glycol butyl ether, 0.2 part offormic acid (90% in water) 15.01 parts of water, 6.0 parts of a siliconebased defoamer, 3.31 parts of carbon black, 5.52 parts of basic whitelead silicate and 2.21 parts of magnesium silicate. When thoroughlymixed, the mixture was ground by passing through a sand grinder.

The pigment paste was then blended with a solution of 15.93 parts of theresin solution described in the first paragraph of this example, 3.24parts of ethylene glycol butyl ether, 9.78 parts of a blockedpolyisocyanate solution at 74.06% solids in a mixture of 52.9% ethyleneglycol methyl ether and 47.1% methylisobutyl ketone, the blockedpolyisocyanate being made from 55.94 parts of a polymethylenepolyphenylisocyanate having an average NCO functionality of 2.4, 9.58parts of methylethyl ketoxime, 6.73 parts of2,2,4-trimethyl-1,3-pentaediol and 27.75 parts of caprolactam, 0.39 partof formic acid (90% in water) and 28.63 parts water.

A dip tank was filled with the aqueous paint reduced to applicationsolids of 30%. Metal objects were totally immersed in the paint, and,after removal were allowed to drip for ten minutes to allow run-off ofexcess paint. The coated objects were then baked for 25 minutes at 193°C. The resulting coatings were well cured and exhibited excellentcorrosion resistance.

It is to be understood that the foregoing detailed description is givenmerely by way of illustration and that many variations may be madetherein without departing from the spirit of the invention.

What is claimed:
 1. A soluble and fusible resinous compositioncomprising the reaction product of(A) a polyepoxide resin derived from adihydric phenol or a dihydric alcohol and an epihalohydrin, saidpolyepoxide resin having a 1,2-epoxide equivalent weight of about 180 toabout 650; (B) an amine mixture of(1) an aliphatic monoamine containingabout 8 to about 18 carbon atoms, one primary amine group and no othergroups reactive with epoxy groups, and (2) an aliphatic diaminecontaining one primary amine group and one tertiary amine group and noother groups reactive with epoxide groups wherein the molar ratio of (1)and (2) in the mixture varies from about 2:1 to about 1:3, and (C) amonoepoxide which contains one 1,2-epoxide group and no other groupsreactive with amine groups, said monoepoxide having about 8 to 24 carbonatomswherein A, B and C are reacted in the mol ratio of 5:6:2 to 2:3:2,and wherein A and C are added to B at a reaction temperature of about50° C. to about 150° C. at an addition rate which does not substantiallyexceed the epoxy-amine reaction rate.
 2. The composition of claim 1wherein the reaction temperature is about 75° C. to about 100° C.
 3. Thecomposition of claim 1 wherein (A) and (B) are reacted first followed byreaction with (C).
 4. The composition of claim 1 wherein the polyepoxideresin is derived from a dihydric phenol and epichlorohydrin.
 5. Thecomposition of claim 4 wherein the dihydric phenol isp,p'-dihydroxydiphenyl propane and the polyepoxide resin has an epoxideequivalent weight of about 350 to about
 650. 6. The composition of claim5 wherein the epoxide equivalent weight is about 425 to about
 500. 7.The composition of claim 1 wherein the aliphatic diamine has the formula##STR3## wherein R is an alkyl group which contains 2 to 6 carbon atomsand R₁ is hydrogen or an alkyl group which contains one to 2 carbonatoms.
 8. The composition of claim 7 wherein the aliphatic diamine is3-diethylaminopropylamine.
 9. The composition of claim 1 wherein thealiphatic monoamine contains 12 to 16 carbon atoms.
 10. The compositionof claim 1 wherein the monoepoxide is an epoxidized unsaturatedhydrocarbon, an epoxidized monoalcohol ester of an unsaturated fattyacid, a monoglycidyl ether of a monohydric alcohol, or a monoglycidylester of a monocarboxylic acid.
 11. The composition of claim 1 whereinthe polyepoxide resin, the amine mixture and the monoepoxide are reactedin the molar ratio of 3:4:2.